A hollow cylindrical tube with a rectangular cross section has external dimensions of 0.5 in. by 1 in. and a wall thickness of 0.05 in. Assume that the material is brass, for which σ = 1.5 × 10⁷ S/m. A current of 200 A dc is flowing down the tube.

(a) What voltage drop is present across a 1 m length of the tube?

(b) Find the voltage drop if the interior of the tube is filled with a conducting material for which σ = 1.5 × 10⁵ S/m.